The invention is generally related to laying of product offshore and more particularly to an arrangement for laying products such as pipe, umbilical lines (umbilicals), and power cables.
A-frames, cranes, and chutes have been used in the past to overboard end terminations of flexible pipes, umbilicals, and power cables (referred to hereinafter as products). In the prior art, these structures have been separate pieces of equipment and not known to be fully integrated together as a single unit.
The separate pieces of equipment and their function are briefly discussed below.
In the most general terms, a vessel is used to transport products to an offshore location where they are to be installed. A tension machine or reel drive arrangement will support the tension generated from the self weight of the product spanning from the installation vessel down to the seabed or between the installation vessel and another fixed or floating platform where the product is being installed to or from.
A chute is used to control the bend radius of the product during laying operations, and is the means of redirecting the product from a generally horizontal plane, over the side (any side including stern), and into the water in a generally vertical plane.
While overboarding the second end, or making connections between two products, a crane or A-frame is used to lift the end termination over the chute while maintaining tangency of the product to the chute.
A hang-off clamp work table is used to support the weight of a product hanging in catenary, while the initiating end of a subsequent product is aligned over the top of the clamped product and the two connected together in a vertical orientation below the chute. The chute is generally fixed at an elevation sufficient to make the connection above the hang-off clamp work table.
A problem with having many different parts that must work together is that the level of complexity for vessel mobilization is increased when installing and configuring all of the different parts in order to work together properly. The amount of time required for installation and configuration is also increased.
Thus, it can be seen that there is a need for an improved product laying arrangement that reduces the complexity and time required for installation and configuration.